Reddit users inquired about fatalities, trespassing and vandalism on the tracks, suicide prevention efforts, when to use the agency’s transit emergency hotline, hostage situations and horn volumes on passing trains. But interest also turned to general service concerns such as service reliability and expansion, reducing delays, wireless Internet access on board, and light-rail transfers for 49ers fans headed to the new Levi’s Stadium in Santa Clara.

Video footage of a man’s close call with a passing express train as he scurried across the tracks, posted to YouTube in February, helped highlight the safety issues that led the transit agency to host the online forum, said Caltrain officials.

“Rail safety is one of our biggest responsibilities as an agency, but we share that responsibility with the public that we serve. We were hoping that this would be an opportunity to engage in a two-way dialogue,” Ackemann said.

Some behaviors near tracks that have been cause for concern are people going around the gate and not being aware of how far the train overhangs the platform, Ackemann said.

“And then, of course, people bicycling and skateboarding at the stations,” she added. “If they slip and fall, they could fall into the path of an oncoming train.”

“We strive to address this issue through the three ‘e’s’ of engineering, education and enforcement to collaborate on solutions,” they wrote.

The agency installs between 10,000 and 20,000 feet of new fencing each year to prevent people and cars from crossing the tracks where they shouldn’t, Ackemann said. Riders who witness unsafe behavior are encouraged to call (877) SAF-RAIL, or (877) 723-7245, a hotline that connects to emergency personnel.

Transit police also work with neighboring law enforcement agencies to raise awareness of rail dangers and conduct targeted citation campaigns against vehicle violations.

According to Ackemann, there are roughly a dozen fatalities each year, 90 percent of which are suicides, along Caltrain’s 77-mile-long corridor between San Francisco and Santa Clara counties. Four to six times per year, trains strike vehicles stopped on the tracks, most of which are unoccupied.

Grade separation projects like the one recently completed in San Bruno seek to minimize incidents by raising trains over intersections and directing pedestrians and cars through underpasses rather than over the tracks.

The new elevated San Bruno station at 833 San Mateo Ave. officially opened Tuesday after three and a half years of construction and the use of a temporary boarding platform for commuters. The San Mateo County Transportation Authority provided 60 percent of the funding for the $155 million safety improvement project.